SonoAlti 3V
Manual and Instructional Video

☠ WARNING ☠

Skydiving is an inherently risky activity that can lead to injury or death. All skydiving equipment is subject to failure. Failure to follow instructions, warnings, and operating procedures could imperil you and others. Every skydiver is solely responsible for his or her safety on each skydive he or she makes. Audible altimeters such as SonoAlti 3V use high sound pressure levels in order to cut through noise and can cause hearing damage. Freefall Data Systems LLC recommends wearing earplugs when using any type of audible altimeter. Altimeters are subject to error and malfunction and should only be used as a secondary indication of altitude—second to a visual ascertainment. It is possible that any altimeter can read higher than the distance you actually are above ground level. Many factors can compromise the accuracy of a barometric altimeter reading, including but not limited to: body position, position relative to other skydivers or objects, altimeter placement, and malfunction. In the end, each skydiver is and must be responsible for their own altitude awareness and safety. Loss of one's own altitude awareness can in certain cases lead to endangering others on the ground as well as in the sky. Many distractions can occur on a skydive; just because you are using an altimeter, it does not mean that you will necessarily register the information it is intended to convey. Additionally, just because two altimeters (e.g. a wrist mounted one and an audio-visual altimeter) are in sync during ascent, this does not necessarily mean that they will be in sync during freefall or under canopy as well, as barometric altimeters are more greatly affected by wakes (burbles) at high speeds than at low speeds. This altimeter contains a lithium ion battery; do not use it if the case is damaged in any way.

LIMITS OF LIABILITY

This product was manufactured for skydiving only. By using this product, you accept full responsibility for its use and agree that you are solely responsible for each skydive you make as well as your safety and that Freefall Data Systems LLC will not be held legally responsible for any malfunction whatsoever that this product may have, whether good or defective.


1.1 SonoAlti 3V Description
2.1 Altimeter Installation and Removal
2.2 Using the 2.5 mm Audio Port
3.1 Using the WebUSB App
3.2 Accessing the WebUSB App
3.3 Main Settings and Metric Mode
3.4 User Presets
3.5 Standard Default Settings and Pre-Loaded User Preset Settings
4.1 Selecting Presets
5.1 Adding User Sounds
6.1 Battery Life
6.2 Charging and Maintaining the Battery
6.3 Checking Battery Status
6.4 Checking Last Jump Info
6.5 Checking Current Firmware
7.1 Firmware Updates and Sharing Custom Firmware Files
8.1 Troubleshooting
9.1 Technical Specifications

1.1 SonoAlti 3V Description

SonoAlti 3V is a speaking barometric audible altimeter with a rugged anodized aluminum case. It has a built-in electromagnetic speaker as well as a 2.5 millimeter audio port that overrides the built-in speaker when an external speaker or earphone is plugged in. SonoAlti 3V has five possible settings. In addition to a standard default setting and a low-speed default setting conceived for wingsuiting, users can set three user presets using an online WebUSB App, described in more detail below. Using the WebUSB App, jumpers can choose custom settings for the three phases of a skydive: ascent, freefall, and canopy. In addition to custom altitude and speed announcements, there are there are 100 pre-recorded notifications or alarms that users can insert at any point in their skydive (e.g. "Pull altitude" , "Check equipment" etc.). Presets can be selected on the fly by pressing and holding the top settings button ⚙ on the altimeter. SonoAlti 3V enables users to set a custom freefall threshold on the user presets; the threshold is 80 mph on the standard default setting and 30 mph on the low-speed default setting, which can be useful for wingsuiters as well as swoopers. Additionally, it allows one to define the range in which ascent, canopy, and freefall announcements occur. SonoAlti 3V automatically adjusts to local elevation, and allows for landing zone elevation adjustments on the user presets, and is always on until the battery is discharged. No settings are lost when the battery has discharged. SonoAlti 3V has a rechargeable lithium ion battery with a life of approximately 100 jumps or six to eight weeks. The battery takes approximately three hours to charge fully. One can check the battery status by pressing and holding both buttons at once (more details below). A low battery warning (a spoken notification at 1,000 feet ) is given if the altimeter has a low battery and does not have much life remaining. It is recommended to charge the altimeter once it reaches 10 percent. Battery life depends on how the altimeter is used and transported. Longest battery life is obtained when the altimeter is stored in one location. SonoAlti 3V can be used with full accuracy as high as 30,000 feet MSL.

2.1 Altimeter Installation and Removal

SonoAlti 3V fits in the audible pocket of most skydiving helmets (most have a pocket created for audible altimeters). The built-in speaker should face the jumper's ear as described in the instructional video above. It is particularly important with speaking audibles that the speaker is as close as possible to the jumper's ear. This may take some experimentation. Unfortunately on some helmets, such as the Kiss, a good fit is unfortunately simply not attainable. Alternatively, when using the 2.5 mm audio port with external audio hardware, the altimeter can be worn on various locations on a jumper's body.


2.2 Using the 2.5 mm Audio Port

The 2.5 mm port disables the built-in speaker when it is used. It is recommended to use the 2.5 mm port in any situation where the built-in speaker is found to be too quiet. Certain external speakers are indeed louder than the internal speaker, and earphones provide the most noise-free result. Many external speakers use a 3.5 mm plug, in which case some type of 3.5 mm to 2.5 mm female-to-male adapter is required to plug them into the jack on the altimeter. Although the altimeter uses mono audio, stereo plugs can be used as well, resulting in a double-mono configuration (e.g. in the case a jumper wants to hear the audio on earphones in both ears).


3.1 Using the WebUSB App

While the two standard default settings as well as the pre-loaded user preset settings, described in detail below, can be used "straight out of the box," modifying the function of the altimeter and setting user presets requires the use of the WebUSB App. The tool has three main settings that affect every preset on the altimeter, including the default settings and three user-programmable presets, making the altimeter extremely flexible. Use of the WebUSB App itself is for the most part self explanatory, as described below.

3.2 Accessing the WebUSB App

It is necessary to use a USB data cable (e.g. the one included with the altimeter) and an internet connection to access the app. A charge-only cable, of which there are very many, will not work to interface with the app. This is one of the most common mistakes users make when attempting to use the app. If your computer does not seem to recognize the altimeter, try a different cable. If the problem persists, try a different computer as well. All of the altimeters manufactured by FDS have their firmware uploaded via the USB port.


Not all web browsers work with WebUSB. Either Chrome or Edge is required to use the app. Make certain that the browser itself is open. It is best not to have the web page for the app open, as the altimeter itself will send a link to the page when connected.


To access the WebUSB app, follow these steps in this order: 1) open the browser you wish to use, either Chrome or Edge; 2) hold down the USB button (the bottom button) on the altimeter until you hear a chime ; 3) plug the altimeter into the computer with a data USB cable; 4) click the link that appears when you plug in the altimeter; 5) set your altimeter (or press the connect button first if the altimeter was not automatically connected).


When finished, do any of the following: 1) simply unplug the altimeter; 2) press the botton button again to leave USB Mode ; or 3) let USB mode time out automatically after two minutes of inactivity.

3.3 Main Settings and Metric Mode

There are three main settings that affect all of the presets on the altimeter, including the two default settings. The first two are a pre-jump and post-jump brief. The pre-jump brief simply informs the jumper at the start of ascent in an aircraft (at 100 feet) what preset the altimeter is on and what the battery status is. The post-jump brief includes exit altitude, the altitude at which the jumpers canopy was fully open (called open altitude), freefall time, canopy time, and battery status. This post-jump information is only said once; to hear it again after completion of a jump, hold down both buttons on the altimeter continuously until past the battery read-out. The third setting is metric mode, for users who prefer kilometers per hour and meters. Note that the freefall threshold on the web app is always in miles per hour.

3.4 User Presets

While the two standard default settings cannot be changed, jumpers can program up to three user presets with their own settings. User presets can include any of the 100 possible notifications contained in the altimeter. As mentioned, the WebUSB App is relatively self explanatory, as it poses questions to the user for each phase of the skydive: ascent, freefall, and canopy. The first question pertains to a possible landing zone offset. For those whose landing zone is, for example, 200 feet higher than their takeoff altitude, 200 should be entered into the text box and the "higher" radio button should be selected. For those landing 200 feet lower, 200 should be entered as well, but the user should select the "lower" radio button. In most cases this should simply be left at 0. Note: A landing zone offset is indicated only during the freefall and canopy descent and not during ascent. For each phase of the skydive, the user is asked whether they want to abbreviate the readings (e.g. “one-eight” vs. “altitude one-thousand eight-hundred feet”). Abbreviation is recommended at least for the freefall and canopy phases of the skydive. Next the user should select how often regular announcements should occur. The options are every 100, 200, 500, 1000, 2000, or 5000 feet or meters, depending on whether metric mode is being utilized. The user should then select whether they want altitude or speed announced or both, using the provided checkboxes. After this, the user can enter the altitudes at which they want these regular announcements to occur. This should generally be left from 0 to 30000 feet/meters (or for ascent from 100 to 30000 feet/meters so one does not hear announcements on the ground at 0 feet). Next, the volume for a particular phase of the skydive is set. 10 is very loud, but is often necessary considering the amplitude of wind noise that occurs on a skydive. Next, the user can select the desired notifications one wants to hear—if any—by selecting from the diplayed box and inputting an altitude next to that notification in feet or meters at which the user wants to hear that particular notification and clicking the "Insert Notification" button. To delete a notification, simply click on the red "X" next to that notification. In addition to spoken notifications, users can select alarms in freefall or under canopy that sound much like those provided by standard audibles (see "Alarm 1" through "Alarm 8"). In addition, the notification "(Altitude)" is available with Firmware 1.1 and higher. This notification will make the altimeter simply read the current altitude at the altitude entered—much like the regular altitude announcements; the altitude entered for this specific notification must be in multiples of 100 feet or meters (e.g. 5100 is allowed but not 5120). Samples of each sound can be heard simply by selecting the notification in the box or viewing the entire list of available sounds here. In the freefall section, one can select a custom freefall threshold, which can be useful for wingsuiters or swoopers. Freefall Data Systems generally recommends wingsuiters start with a value of 40 mph and work their way lower for larger suits. A value as low as 20 mph can be set for those involved in XRW or other flights with very low descent rates. Swoopers might input a value upwards of 100 mph or even higher as to ensure they do not hear freefall announcements or notifications under canopy. Another option is to set the freefall threshold extremely high (e.g. 500 mph), which enables a wingsuit flyer to work simply with the canopy notifications for both flight and canopy.

3.5 Standard Default Settings and Pre-Loaded User Preset Settings

SonoAlti 3V contains two standard settings that cannot be changed by the user (aside from being affected by the main settings described above). The Standard Default Setting simply reads off the altitude every 2000 feet or meters on ascent and every 1000 in freefall, and then every 500 under canopy. The freefall threshold is 80 mph. The Low-Speed Default Setting is conceived for wingsuiting, with a freefall threshold of 30 mph; announcements are made every 2000 feet/meters on ascent, every 500 feet/meters in freefall (e.g. in wingsuit flight) as well as under canopy. Regardless of the preset, speed is always indicated in feet or meters per minute during ascent and under canopy, and in miles per hour or kilometers per hour in freefall. No notifications are provided when using the default settings, but they are sufficient for most purposes.


User Presets, although they can be changed as described above, also come with pre-loaded settings. They are the settings that come with the altimeter or those that are present in the firmware files that can be found on the FDS website. The pre-loaded user preset settings are the same as the Standard Default Setting, but come with the addition of a few notifications as well. User Preset 1 comes with a seatbelt notification at 1500 feet, and a breakoff notification at 6000 feet, as well as a pull notification at 4500 feet. In a similar fashion, User Preset 2 comes with a seatbelt notification at 1500 feet, and a breakoff notification at 5500 feet, and a pull notification at 4000 feet. Finally, User Preset 3 comes with a seatbelt notification at 1500 feet, and a breakoff notification at 5000 feet, and a pull notification at 3500 feet.

4.1 Selecting Presets

The settings button ⚙ on the altimeter can be used to select a preset. If one presses and holds the settings button on the altimeter, one will hear the altimeter indicate the currently selected preset. If one presses and holds a button shortly thereafter again, or keeps holding a button, the altimeter will cycle through the five available settings. Presets can be selected on the ground and during ascent in the aircraft, but the button becomes inactive during freefall and under canopy. Freefall Data Systems always recommends setting the altimeter on the ground before a skydive.

5.1 Adding User Sounds


Adding user sounds is only recommended for tech-savvy users or with help from FDS. To add user sounds, follow these steps: 1) Use Audacity, which can be found here, to create a WAV file in 44.1 kHz 16-bit mono format (using PCM). The file should be made to be as loud as possible, even accepting some clipping to make it louder particularly for speech. The file should be short. 2) Save the file to your computer in this format, making certain to title the file beginning with a capital letter. 3) Download the Flash Revealer file. 4) Plug your altimeter into the computer using a data USB cable. 5) Double tap the reset button (using a paperclip in the small hole adjacent to the speaker) on the altimeter (a quick double tap is necessary) to reveal the altimeter on your desktop as a drive called "SonoAlti 3V". 6) Drag the "SonoAlti_3V_16MB_Flash_Revealer.uf2" onto the "SonoAlti 3V" drive. 7) The drive should appear with a new name. 8) Click on the drive to open it. 9) Drag your sound file into the "SonoAlti_3V_Sounds" folder on the drive and wait until it has finished copying. 10) Double click the reset button (using a paperclip in the small hole adjacent to the speaker) again on the altimeter to reveal "SonoAlti 3V" once again. 11) Drag the latest firmware file (e.g. "SonoAlti_3V_Firmware_1_0.uf2") from here onto the altimeter. 12) You should hear "Success ..." after doing this. 13) Your file will now appear alongside the other sounds (at the bottom of the lists) in the WebUSB App for all phases of the skydive when you connect your altimeter.

6.1 Battery Life

SonoAlti 3V's battery typically lasts approximately 100 jumps or six to eight weeks. Digital altimeters subjected to long car rides through hilly or mountainous terrain will naturally discharge the battery faster. The longest battery life is obtained by leaving the altimeter in one location. Simply driving with the altimeter to work in normal circumstances, however, will not significantly reduce the battery life of SonoAlti 3V.

6.2 Charging and Maintaining the Battery

SonoAlti 3V has a lithium ion battery that is rechargeable with the included USB data cable. It takes approximately three hours to fully charge an empty battery. A red LED indicates that the battery is charging, and this LED will go off to indicate the altimeter is done charging. It should only be necessary to recharge the altimeter periodically, as it was designed to have a long battery life. It does not harm the altimeter, however, to charge it often. During long periods of storage (e.g. winter months), the altimeter should ideally be charged once every two months in order to preserve battery life. It is best to store the altimeter in a cool, dry place.

6.3 Checking Battery Status

Holding down both buttons on the altimeter will have the altimeter read off the current battery status in percent. If one is using metric mode, the altimeter will also indicate this after the battery status is read.

6.4 Checking Last Jump Info

If you continue holding down both buttons on the altimeter after the battery status has been read, you will hear the following information regarding the last jump: exit altitude, open altitude (meaning the altitude at which the canopy was fully open), freefall time, and canopy time. This can be useful for logging purposes. Note: This information is lost when the battery on the altimeter runs out or when the altimeter is reset.

6.5 Checking Current Firmware

If one continues holding down both buttons on the altimeter after the battery status and last jump info have been read, the current firmware will be indicated.

7.1 Firmware Updates and Sharing Custom Firmware Files

To update the firmware, follow these steps in this order: 1) Plug the altimeter into the computer using a data USB cable (it must be a data cable). 2) Double tap the reset button (using a paperclip in the small hole adjacent to the speaker) on the altimeter (a quick double tap is necessary) to reveal the altimeter on your desktop as a drive called "SonoAlti 3V". 3) Drag the latest firmware file (e.g. "SonoAlti_3V_Firmware_1_0.uf2") from here onto the altimeter. 4) You should hear "Success ..." after doing this. Updating the firmware returns the settings to the factory defaults, so all user presets will need to be reprogrammed if desired.


The exact same process is used to share custom firmware containing user presets: 1) Plug the altimeter whose settings you want to copy into the computer using a data USB cable (it must be a data cable). 2) Double tap the reset button (using a paperclip in the small hole adjacent to the speaker) on the altimeter (a quick double tap is necessary) to reveal the altimeter on your desktop as a drive called "SonoAlti 3V". 3) Click on the drive and save the file called "CURRENT.UF2" to a location on your computer. Take another SonoAlti 3V altimeter, and carry out the same process, but copy over the "CURRENT.UF2" file on its drive with the file from the first altimeter (the presets are stored in the firmware).

8.1 Troubleshooting

If you hear your altimeter on the ground, turn off the pre-jump briefs or change your Ascent for the preset you are using where the app asks, "In what altitude range should these regular announcements be given?" Change the lower number to something higher than 0, because 0 means you want it to read on the ground.

If the altimeter fails to function on a skydive, first make sure the altimeter is charged. Next, if the altimeter is charged, see if you can select a preset on the unit on the ground to see if it is responding as expected (press and hold the top button). Perhaps the wrong preset was selected. If the altimeter does not respond to any type of button presses, insert a small paper clip into the small hole adjacent to the speaker and depress the manual reset button a single time (you should feel the button slightly give way). This will reset the unit, which takes several seconds. You should hear the altimeter indicate that it is ready for operation. If all of this fails to solve the problem, visit the FDS Forum or contact Freefall Data Systems LLC for further assistance.

9.1 Technical Specifications